Questions tagged [noise]

Questions related to aviation sound noise or regulations thereof.

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64
votes
4answers
68k views

Why does the Boeing 787 engine nacelle exhaust have such an unusual shape?

Why does the Boeing 787 nacelle have this unique shape at the exhaust: I haven't seen it on any other airplanes, does it serve an aerodynamic purpose or help engine efficiency or is it just to look ...
54
votes
4answers
21k views

Can I stop crop dusters repeatedly flying over my home?

I have a crop-duster spraying the fields around me often. He flies over my house no matter what field he is spraying every few minutes. I think he uses my house as a pivot point. The old pilot rarely ...
35
votes
1answer
9k views

Why was there a rattling noise coming from the left engine of A319?

I recently flew on an Airbus A319. When boarding the aircraft from the front entrance we passed in front of the left engine. The fan blades were spinning and there was a rattling noise (like when a ...
33
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2answers
7k views

Why don't modern jet engines use forced exhaust mixing?

Jet engines are noisy[citation needed] - even a modern high-bypass turbofan is still deafeningly loud compared to pretty much anything except the even-louder low-bypass turbofans or a turbojet (much ...
26
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3answers
5k views

Why would a turboprop rev down just before going full throttle during takeoff?

The only turbprop I've travelled is the ATR 72. I've noticed that the props' rev go down (for like a second, the sound also goes down) just before engaging full throttle in order to takeoff. I've ...
22
votes
9answers
7k views

Why are winches not used for towing commercial planes up?

In this video a glider is pulled up by a winch on the ground, like this: (Source) I would say you could apply the same principles with bigger planes, possibly even using sustainable energy sources. ...
22
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2answers
22k views

Do helicopter rotor tips regularly go supersonic?

In my question about helicopter noise, I made the assumption that one reason they are so darn noisy is that the main rotor tips go faster than the speed of sound. @FreeMan questioned whether that was ...
21
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4answers
7k views

Are seaplanes allowed to taxi in residential areas?

There's a small pond/lake behind my house. A sea plane was just going around it. It was very loud and got like 10 feet from the shore. It's just going in circles and won't take off and leave. This is ...
20
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3answers
8k views

Why don't airliners use noise cancelling?

Some cars have started using noise cancelling in their cabins, through the speaker system. It's a well established technique for dealing with low frequency noise like engine rumble and wind noise. So ...
20
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3answers
5k views

Why aren't modern helicopters quieter?

Living closer to a Sikorsky factory, I can attest that modern civilian (and military) helicopters are quite noisy. In any case, they are considerably louder than light aircraft, turboprops, and even ...
20
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2answers
2k views

How do turbofan nacelle lengths compare?

For example, compare the JT9D and the PW4000 below (both from Pratt & Whitney, both on a 747): (Left, Right) The PW4000 has a longer forward nacelle, and a covered exhaust cone. On the inside—...
18
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6answers
6k views

Is an afterburner louder than the same jet engine without it?

I would speculate that an afterburner increases the noise because it is nearer to the exhaust. But it certainly causes so many changes in the exhaust flow that it could be less loud as well. It may ...
18
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3answers
3k views

Does a Mach 1 plane hear a sonic boom from a Mach 3 plane overtaking him?

Let's say Bob is flying at Mach 1 and then John, in another aircraft, overtakes him at Mach 3. They are flying parallel to each other, say 500 meters apart. And there is no wind. Their relative speed ...
18
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3answers
2k views

When a typical commercial airliner flies overhead, what is the actual noise we are hearing?

We're all familiar of the sound planes flying quite high overhead and you hear a faint drone, even when planes are lower to the ground you hear them scream at a slightly higher pitch, but what exactly ...
18
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3answers
27k views

What causes descending aircraft to make a noise like a giant blown bottle?

I've lived for years about eight miles NW of Boston's Logan Airport. Although I can't say we get a lot of aircraft noise, once in a while, due to winds or air traffic, there will be a long line of ...
17
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2answers
5k views

Are there any reported cases of noise from helicopters causing damage to property?

In the Netherlands, three cases have been reported of Chinook helicopters' rattle noise (low frequency sound) damaging solar panels. The Dutch defense ministry recognises this problem and the lawyer ...
17
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3answers
3k views

Won't sonic booms prevent Space X's BFR intercity transport plan from being acceptable?

Considering that Space X have just announced that their BFR can take anyone anywhere in the world in under 1 hour, that would be enormous speed, does this rocket not produce sonic boom? If not is it ...
16
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2answers
8k views

What is the loud noise of a helicopter when the rotors are not yet moving?

What is the loud noise when a helicopter is ready to start flying, but the rotor is not yet rotating? For example at Trump's "chopper talk", when he is intercepted by reporters on the way to Marine ...
15
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3answers
3k views

Do nacelles around aircraft engines help in reducing the engine sound?

I know that the nacelles around the aircraft engines are actually a housing and are generally lightweight and have may components like inlet cowl, fan cowl, etc., but do they help in reducing the ...
15
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3answers
6k views

Why does a jet engine acquire a metallic whine when in full power? [duplicate]

I had a flight yesterday on an AA Embraer ERJ-190. As the plane idled at the end of the runway there was the familiar high-pitched jet whistle, which increased in pitch as the engine started spinning ...
14
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4answers
2k views

What noises can you hear as a passenger?

I'm just curious as to what the noises are that you can hear as a passenger in the cabin of an airliner? For example (ignore the crew talking), the noise at 7:09 - 7:30 on this video; is that the ...
13
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2answers
6k views

Can pilots hear their passengers clapping on touchdown?

Something that just popped into my head: I've been on a few easyJet and Ryanair flights where a lot of passengers clap and cheer on touchdown. Would the pilots be able to hear this? Here's an example ...
13
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5answers
2k views

Can an experienced airplane spotter identify planes only by sound?

I come from a background in railroad watching, and often times one can identify the maker of a railroad locomotive purely by sound. Maybe not the exact model of locomotive, but at least what type of ...
12
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5answers
10k views

What could explain the fact that during 1976-80, I used to hear commercial jets make sonic booms while flying overhead?

I've read on this site & on Wikipedia that there have only been a couple of commercial jet planes in history that have broken the sound barrier--either in testing (without passengers) or during an ...
12
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1answer
2k views

Why do flying wires hum louder in a sideslip?

Page 50 of the Feb. 2021 issue of the EAA's magazine Sport Aviation reports that Like any good vintage airplane, the Sea Bird likes to fly coordinated, and the flying wires will sing out loud if the ...
12
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2answers
2k views

Can noise from contra-rotating propellers be reduced by having a different number of blades on each propeller?

Heads up: This came from Wikipedia's page on contra-rotating propellers and it explicitly says citation needed: However they can be very noisy ... It is also helpful if the two propellers have a ...
12
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1answer
7k views

What is the buzzing noise generated by the engines in this 777 takeoff video?

I've flown a few times in my life, both in economy and executive class. Every time I fly in executive, during takeoff, there is a different noise from the engines. In economy class (behind the engines)...
12
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1answer
5k views

What causes the distinct sounds of a jet engine?

I live a few miles from a major airport (BOS), under the path that a lot of airplanes use to depart. The planes are somewhat low over my house -- high enough that it's not deafening, but low enough ...
12
votes
1answer
2k views

What causes the sudden spool-up sound from an F-16 when enabling afterburner?

What causes the sudden spool-up sound from an F-16 when enabling afterburner? I've included a video to make it clear what sound I'm referring to: at 1:16, I assume ...
11
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5answers
4k views

Is landing without engine power routinely feasible?

Considering that airplanes are very noisy, could one routinely land them with the engines turned off, gliding onto the runway? Could the engines be started fast enough for an emergency situation?
11
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2answers
3k views

Why is a Lockheed MC-130J Commando II creating such a loud droning sound?

Today I heard a loud droning sound which is really unusual in the area of west London I live in; so I went on ADS-B exchange and it showed a USAF Lockheed MC-130J Commando II flying literally right ...
11
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6answers
3k views

Is ear protection necessary for General Aviation aircraft?

What would happen if someone flew a brand new Cessna Skylane/Caravan or a Robinson R22 without using earplugs or headphones? Would they get hearing damage or it would be just a little bit loud where ...
11
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2answers
1k views

Can an airport fine an aircraft for being too noisy?

I stumbled upon this article (sorry, in French!) stating that in order to avoid fines, Ryanair pilots start take-off procedures at the beginning of the runway (rather than at the "intersection"), with ...
10
votes
1answer
5k views

Will you be able to hear a supersonic aircraft flying away from you?

I'm wondering if you could be able to hear the sound emitted by an aircraft say traveling at Mach 2 away from you. I wondered if it might shift the emitted frequencies beyond the audible range. Would ...
10
votes
3answers
7k views

Why are light aircraft engines so noisy?

I live near an airport where students spend a lot of time flying circuits. During the base leg, pilots can be heard reducing engine revs prior to the final left/right turn to line up with the runway. ...
10
votes
1answer
1k views

Is ultrasonic noise from small turbines painful to pets?

A question on another SE site prompted me to search for 'Aircraft engines untrasonic noise dogs', but with not much success. The OP's dog barked like crazy at turboprops, but was not bothered at all ...
10
votes
1answer
737 views

In a piston aircraft, how much noise is generated by the engine, and how much by the propeller?

I've been reading quite a few articles lately about how noise complaints from GA airports across the country. One of the common suggestions to fix the issue is to simply use an electric engine ...
10
votes
1answer
540 views

Will an airliner with a quieter cabin have a quieter cargo hold?

I am aware that this question is on the border of travel and aviation but nobody on the travel side of the fence seems to be able to answer it. Apologies if it is regarded as off-topic for this site. ...
10
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0answers
2k views

How loud was the Concorde's sonic boom at the ground level? [duplicate]

Before the Concorde was sent into retirement, their supersonic flight paths were restricted to the ocean because of concerns about sonic boom on the ground. But just how loud was this boom? Was it ...
9
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5answers
3k views

Does any of the hearing protection worn by aviation professionals use active noise reduction?

I have read that passive hearing protection (standard earmuffs/plugs) offer good protection against higher frequency noise but do not protect as well at lower frequencies. Supposedly active noise ...
9
votes
7answers
13k views

How do the cabin noise levels of the A380 and the 777 300 ER compare?

I couldn't find any official comparison for noise level (dB) in Airbus A380 versus the Boeing 777 300 ER. Does anyone have some info about it? Which one is better in terms of acoustic isolation?
9
votes
1answer
935 views

Why does the chevron-shaped engine suffer losses in thrust performance?

From here I found out a lot about chevrons on the Boeing 787, but not enough to satisfy why it results in performance loss. My thinking was originally, if they are "cutting triangular holes" in the "...
8
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3answers
4k views

Do quadcopter propellers break the sound barrier?

I recently bought a quadcopter and noticed every time I fly it there is this weird buzzing noise. I have heard this noise on other quadcopters around the same size as mine(4in by 4in). On an airliner ...
8
votes
2answers
370 views

Are there any methods to predict the location of a jet aircraft from its sound?

At times there are military fighter aircraft flying overhead of my location (MiG-21Bis and Su-30MKI). The first indication of their presence being the sound, that obviously causes one to look up to ...
8
votes
1answer
1k views

What is the major source of engine noise for non-propeller aircraft?

Sparked by this question: Take any non-propeller powered aircraft, when idle, the sound produced by the engines are fairly low pitched, and as the engine spins up, increasing in pitch before becoming ...
8
votes
1answer
916 views

What does aerodynamic noise of an airliner sound like in landing configuration?

I want to know what aerodynamic noise an airliner makes when flying with both engines shut down. Specifically, it is the sound made by air passing a plane which is in landing configuration, with gear ...
8
votes
2answers
522 views

How much noise does flow separation cause?

I recently found the following image showing the different sources of noise in vehicles. I notice that Aerodynamics is actually quite a big part of vehicle noise, as shown below by the blue line: ...
8
votes
0answers
661 views

Why are the cabin chimes one semitone lower on the Boeing 747-400 than on other aircraft? [closed]

I noticed that the cabin chimes on the Boeing 747-400 overall sound one semitone lower than on other aircraft, including the 737, 777, Airbus A320, and even the 747-8. The same semitone-lower chimes ...
7
votes
3answers
1k views

Do ANR headsets affect pilots' perception of engine problems?

ANR (Active Noise Reduction) headsets reduce the sound level to a pilot's ears by creating an interference wave that cancels out some of the environmental noise in the cabin. Some say that this ...
7
votes
3answers
9k views

Which light aircraft are known to have a quiet cockpit?

Are some light aircraft known as being significantly quieter in the cockpit than others ? How quiet might the quietest light aircraft be from the inside ? At least ten years ago I was reading an ...